Wednesday, 8 June 2011

MBTs - do they do what they say! - An interesting article

MBTs - How effectively can MBT they be used to combat bad walking patterns and reduce injuries?

Masai Barefoot Technology trainers (MBTs) have been around for 10 years, but lately are showing signs of becoming high-fashion must-have items. The makers claim that the shoe:

·activates neglected foot muscles

·improves posture

·tones and shapes the body

·improves performance

·helps with back, hip, leg and foot problems

·helps with joint, muscle, ligament and tendon injuries

·reduces stress on the knee and hip joints

The international media hype around MBTs has even gone so far as to suggest that the shoes can help banish cellulite and promote weight loss – claims not far short of alchemy.

MBT is based on a simple concept: that the human foot is designed for barefoot walking on soft ground, yet most of us in developed countries spend our lives in supportive and restrictive footwear and walk on hard, flat surfaces. The shoe design is the brainchild of Karl Muller, a Swiss engineer, who derived his inspiration from the low injury rates of the African continent.

Leaving aside the obvious differences between the functional requirements of a Masai tribal member and the average inner-city office worker/amateur athlete, does this shoe design add up to anything more than a gimmick in terms of injury prevention?

Ordinary shoes do little to correct poor gait (walking style). Most of us prioritise comfort or fashion over our specific functional or anatomical needs, with the result that we adopt a passive gait, in which the foot, ankle and leg muscles become under-worked and develop weaknesses.

Strong intrinsic foot musculature is what allows the tissues of the foot and ankle to tolerate the stresses of instability effectively and without damage or injury. It is therefore not unreasonable to suggest that areas of weakness can also be prime sites of potential injury. There is no reliable evidence that yet proves you can strengthen specific muscles by wearing a particular type of shoe.

The MBT was designed as a medical shoe. It is a slightly unsightly, bulky shoe, with a substantial thick sole that is curved from front to back, forcing a pronounced heel-to-toe walk. The unstable rocking action is thought to simulate the natural instability of walking over undulating ground and thereby encourage beneficial muscle strengthening.

To date there appear to have been three main scientific studies on the MBT trainer and its effect on how we walk.

The first research came from the Human Performance Laboratory in Calgary, Canada. The MBT was shown to:

•decrease ankle joint impulses for the knee joint, which means that the knee has to withstand fewer repetitive rotational stresses (down by 27%)

•increase the wearer's oxygen consumption by 2.5%

•increase movement of the 'centre of pressure' (COP) during standing, which allows force to be spread across a greater area of the foot. High forces going through small areas of the foot are strongly linked to an increase in injury levels with repetitive foot strikes over prolonged periods.

Based on these findings, the researchers report that the MBT strengthens the muscles of the foot and ankle complex, while reducing loading through the ankle joint. But this study had small numbers (eight people) and conducted its analysis at relatively low walking speeds, which limits its value.

The second relevant piece of research was a gait evaluation study from Sheffield Hallam University. The researchers found:

•less forward lean: MBT promotes a more upright posture, which may affect the position of the centre of mass at foot strike. The further the distance of the foot when making contact with the ground the greater the braking forces that occur on the body.

•The authors imply that the MBT reduces braking forces, which does make mechanical sense, as anything that promotes a more upright posture tends to lead to a more efficient system and reduced load through the body

•higher dorsiflexion ankle angle: The shoe's rocker system forces the foot into a greater flexed position throughout the walking cycle. This would promote a rolling of the foot, which would distribute forces evenly through the feet, allowing the body to absorb force quickly, without injury

•reduced 'transient peaks' with MBTs: momentary forces sent through the skeleton as a result of impacts during normal walking and running are a primary factor in the development of many musculoskeletal disorders

•MBTs allowed increased muscle activity in the calf, hamstring and buttock muscles, but a decrease in the small postural muscles of the spine, perhaps because of the more upright posture and production of greater propulsive forces.

A third research group, from Edinburgh, compared foot pressures during gait among 22 subjects wearing MBTs and normal trainers. For the MBTs, it found:

•reduced foot pressure in the heel (probably the result of the MBT design in which there is no cut-away on the heel section)

•average pressure was greater in the toes and forefoot and less in the mid foot and heel

•a shift in the pattern of the centre of pressure, allowing force to be spread over a greater area of the foot.

People suffering with conditions such as osteoarthritis or other degenerative joint disease may benefit from the reduced joint loading of the MBT's heel-to-toe rocker. But because the rocker sole runs front to back, the shoe is primarily designed for 'single plane' activities such as walking or linear jogging. And the large and bulky sole unit may add to the shoe's unsuitability for multi-directional sports (eg, squash, tennis or team sports) where shoe feel, lightness, durability etc are important.

While there are manufacturer's claims for the MBT's efficacy in relation to jogging, there is no evidence to support them. Athletes using a more pronounced mid foot or even forefoot strike with the ground will find this kind of sole design irrelevant.

The bottom line -No single piece of technology can substitute for a well-structured and balanced conditioning programme that includes foot musculature strengthening. As things stand, it would be playing safe not to throw out all your other trainers/shoes for a life in MBTs.